Catheterization procedures guided by x-ray fluoroscopy are widely done in medicine for diagnostic and therapeutic interventional purposes. The fluoroscopist who is manipulating the catheter for the procedure must be shielded from excessive radiation exposure. Most of the radiation that reaches the fluoroscopist is scattered from the volume of the patient's tissues that are in the direct path of the imaging x-ray beam, which usually is projected from a source usually located beneath the platform upon which the patent is supported. Shielding is typically done by the use of shielding garments worn by the fluoroscopist, including a protective apron to shield the trunk of the body, possibly supplemented with a thyroid shield around the neck, lead glasses etc. The intensity of scattered radiation is greatest at points on the patient that are near the irradiated field margins. The fluoroscopist's hands are in contact with the patient during manipulation of the catheters and typically receive the highest radiation exposure. Because the hands are working within a sterile field any solution for shielding the hands must be rendered biologically sterile but should not block the image field that is currently viewed on the fluoroscope. Because the shielding material becomes biologically contaminated with blood and other body fluids it is preferable that it is disposable or is enclosed in a disposable sterile sheath. If disposable the shielding material should not contain toxic metals like lead which would contaminate the waste stream.
There are two existing products that are designed to shield the hands, both meet the needs to some respect but both have significant drawbacks. Product 1 consists of a flexible sterile glove made of an elastomer that incorporates one or more heavy metal attenuating powders in the elastomer matrix. Product 2 consists of a flexible pad made from an elastomer charged with one or more heavy metal attenuating powders in the elastomer matrix, and covered with a sterile over-layer. The gloves are designed to replace the standard thin latex surgeon's gloves that are employed in all surgical operations but adding a shielding component. The main drawback for these gloves is that there is a tradeoff between a thin flexible material that easily permits manipulation of thin catheters and other instruments and the degree of protection provided by the material. Disposable single-use gloves that are sufficiently flexible typically provide less than 50% attenuation. The high cost relative to its low level of shielding effectiveness makes this product a poor choice. The sterile flexible pads of product 2 (see for example U.S. Pat. No. 4,938,233) are far more effective in providing shielding of the hands, The pad is placed directly on the patient's body directly over the catheter access site with a cut-out to provide access. The flexible shield is constructed to have sufficient attenuation to reduce the radiation exposure to the hands by 75% or more. Because the pads can be relatively large, they can shield a greater region of the fluoroscopist's body than just the hands. These pads however have two significant drawbacks. The first drawback is that the pads are relatively heavy and when positioned correctly on the patient, they hang over the side of the patient's body facing the fluoroscopist. To keep them in place the pads have an adhesive tape backing that sticks to the large loose sterile drape that covers the patient's body. This position hanging off the side the patient however makes the drape susceptible to sliding to the floor taking the sterile drape and all the instruments with it. If this should occur the patient must be re-draped and all the sterile instruments must be replaced. Potentially this problem could be addressed by a fixture or method that attaches drapes to the patient; however there is a more serious drawback. The second drawback is that the shielding material, while reducing radiation exposure to the fluoroscopist and staff can significantly increase the exposure to the patient in ways that would not be obvious to the clinical staff. The problem relates to the function of the automatic exposure control (AEC) system used in virtually all fluoroscopes. The AEC system automatically adjusts the x-ray machine exposure rate to compensate for variations in the attenuation in the patient to ensure that fluoroscopic image quality remains constant regardless of the body thickness or density. Normal fluoroscope operation configures the x-ray source below the patient with the image receptor above. Pad type shielding materials are placed on the upper surface so that if the fluoroscopist moves the fluoroscope so that the beam encounters the shield, the automatic exposure control will increase the exposure rate sufficiently to penetrate through the shield. This substantial increase in exposure rate is received by the patient and is greatest at the skin surface where the x-ray beam enters; this is not in the best interest of the patient. The purpose of the invention is to provide a shield that is more effective than the gloves and at least as effective as the pad type devices but without the drawbacks of potentially sliding off the patient or substantially increasing the patient radiation dose.